This invention relates to a sample cup for use in accommodating specimens for spectrochemical analysis in general and more particularly to such a cup including selectively operated venting means.
Technological advancements in both wavelength-dispersive (WD-XRF) and energy dispersive (ED-XRF) x-ray fluorescence instrumentation have furnished the spectroscopist the means to accommodate virtually all types of sample materials submitted for analysis.
In this technology sample cups are employed to hold or contain the liquid, solid and powdered specimens under normal atmospheric pressures, gas pressures or in vacuum for performing analysis on the contained sample using the above and other techniques.
As such, sample cups are well known. Many prior art sample cups consisted of three components as a cup-shaped cell having a closed bottom and an opened top, an annular collar and a snap-on ring used to hold a sheet of plastic after insertion of the sample and for closing the opened top prior to spectroanalysis. A typical prior art sample cup is shown in U.S. Pat. No. Des. 238,693 entitled CELL FOR X-RAY SPECTROSCOPY OR SIMILAR ARTICLE issued on Feb. 3, 1976 to Monte J. Solazzi.
Sample cups or cells are available in many different configurations such as those sold by Chemplex Industries of 140 Marbledale Road, Eastchester, NY 90707, the assignee herein.
Many sample cups require venting means whereby a hole or aperture is formed in a closed surface of the cup to enable the equalization of pressure.
The reasons a vent is required has been explained in great detail in the Background of the Invention as specified in U.S. Pat. No. 4,409,854 entitled SAMPLE CUP WITH VENTING MEANS FOR USE IN X-RAY SPECTROSCOPY issued on Oct. 18, 1983 to M. C. Solazzi and assigned to the assignee herein. In that patent there is described a sample cup which includes on the bottom surface of the cell an upstanding plunger positioned within a thinner area of the surface. The plunger has grooves directed from top to bottom on the side walls and when depressed ruptures the closed bottom of the cell to create the vent necessary to equalize the pressure.
Essentially, the formation of the vent as disclosed in the above noted patent as well as in other prior art devices causes a permanent rupture or breakage of the cell body, and hence once a vent passage is accommodated, the cell is permanently damaged as containing a permanent vent and therefore a closed cell condition cannot be obtained again.
It is an object of the present invention to provide an improved sample cup having selectively operated venting means whereby the cup can be vented in a first mode and then fully closed in a second mode and revented again and so on.
This is accomplished by means of a snap-on rotatable cap which coacts with a cylindrical cell body. Both the cap and the cell body possess corresponding venting apertures to enable alignment of the apertures in a venting mode and to close the cup when the apertures are out of alignment.
The structure of the cell eliminates the necessity of the user to form venting apertures by the use of a sharp tool or by employing other venting mechanisms of the prior art.